AquaCal
AquaCal Pool Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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AF
Display shows AF or AIR FAIL; the unit will not start or shuts down shortly after a fan start attempt.
Airflow / Fan Failure
CO
Display shows CO or COMM; the heater does not respond to remote commands.
Communication Error with External Controller
dF
The display shows dF or DEFROST; the unit stops heating and may run the fan only.
Defrost Mode Active
dP
Display shows dP or DP; the heater shuts down due to a water pressure/flow differential fault.
Water Pressure Differential Fault
EE
Display shows EE or EEr; the unit is non-responsive or stuck in an error state.
Internal Control Board Error
FL
The display shows FL or FLO; the unit will not start heating and may show a water flow icon or message.
Insufficient Water Flow / Flow Switch Open
FS
The display shows FS, and the heater will not start or shuts down shortly after starting.
Water Temperature Sensor Fault
FS1
The display shows FS1; the heater will not operate or operates erratically.
Water Inlet Temperature Sensor Fault
FS2
Display shows FS2; the heater may shut down or refuse to start.
Water Outlet Temperature Sensor Fault
HC
Display shows HC or HEAT COOL CONFLICT; the unit may not start.
Conflicting Heat/Cool Command
HI
The display shows HI or HIGH TEMP, and the unit shuts down; water may feel very warm near the heater outlet.
High Water Temperature Lockout
HP
Unit displays HP and shuts down; pool water is not heating, and the compressor stops shortly after startup.
High Refrigerant Pressure Trip
HPS
Display shows HPS; the unit shuts down due to a safety lockout.
High Pressure Switch Open
LO
The display shows LO or LOW TEMP, and the unit will not start or cycles off quickly.
Low Ambient Air Temperature Lockout
LOP
Display shows LOP or LOW PUMP; the heater will not run.
Low Pump Speed / Flow Detected
LP
The unit displays LP and will not heat; the compressor may attempt to start and then shut down.
Low Refrigerant Pressure Trip
LPS
Display shows LPS; heater will not run.
Low Pressure Switch Open
OF
The display shows OF or OFF, and the unit will not respond to thermostat changes.
External Control or Service Mode Active
PF
The display shows PF or POWER FAIL; the unit may reset unexpectedly or lose settings.
Power Interruption / Low Voltage Fault
rF
Display shows rF or REF; the unit will not heat and may lock out.
Refrigeration System Fault
SE
Display shows SE or SENSOR; the heater locks out.
General Sensor Circuit Error
tS
Display shows tS or TIMEOUT; unit attempts to start but times out.
Startup Timeout / No Heat Produced
Symptom
Display shows normal operation, but the fan does not run; the unit may shut down on high pressure.
Fan Not Operating
Symptom
Heater causes excessive vibration transmitted to pad or nearby structures.
Vibration / Mounting Issues
Symptom
Heater display is on but unit does not respond to button presses.
Unresponsive Keypad / User Interface Failure
Symptom
Heater is running but making loud grinding, squealing, or rattling noises.
Mechanical Noise from Fan or Compressor
Symptom
Heater runs but pool water does not reach set temperature; unit cycles on and off frequently.
Insufficient Heating Capacity or Short Cycling
Symptom
Heater trips the GFCI or breaker shortly after starting.
Electrical Ground Fault or Overcurrent
Symptom
Heater will not start at all; display is blank or dim.
No Power to AquaCal Heater
Symptom
Strong chemical or burning smell around the heater during operation.
Overheating Electrical or Chemical Off-gassing
Symptom
The fan runs, but the compressor does not start; no heating occurs.
Compressor Start Failure
Symptom
The heater cabinet shows corrosion, rust, or paint bubbling, especially near the coil and base.
Environmental Corrosion Damage
Symptom
The heater frequently goes into defrost and spends long periods not heating, even in mild weather.
Excessive Defrost Cycling
Symptom
The heater frequently shuts off when it rains or after heavy splashing from the pool.
Moisture Intrusion into Electrical or Sensor Components
Symptom
The heater operates, but causes a noticeable drop in water flow to pool returns.
Excessive Flow Restriction Through Heater
Symptom
Water leaking from the base of the AquaCal heater.
External Water Leak
Symptom
Water temperature overshoots the setpoint by several degrees before the heater shuts off.
Thermostat Overshoot / Control Hysteresis Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| AF |
Display shows AF or AIR FAIL; the unit will not start or shuts down shortly after a fan start attempt.
|
Airflow / Fan Failure | View Details |
| CO |
Display shows CO or COMM; the heater does not respond to remote commands.
|
Communication Error with External Controller | View Details |
| dF |
The display shows dF or DEFROST; the unit stops heating and may run the fan only.
|
Defrost Mode Active | View Details |
| dP |
Display shows dP or DP; the heater shuts down due to a water pressure/flow differential fault.
|
Water Pressure Differential Fault | View Details |
| EE |
Display shows EE or EEr; the unit is non-responsive or stuck in an error state.
|
Internal Control Board Error | View Details |
| FL |
The display shows FL or FLO; the unit will not start heating and may show a water flow icon or message.
|
Insufficient Water Flow / Flow Switch Open | View Details |
| FS |
The display shows FS, and the heater will not start or shuts down shortly after starting.
|
Water Temperature Sensor Fault | View Details |
| FS1 |
The display shows FS1; the heater will not operate or operates erratically.
|
Water Inlet Temperature Sensor Fault | View Details |
| FS2 |
Display shows FS2; the heater may shut down or refuse to start.
|
Water Outlet Temperature Sensor Fault | View Details |
| HC |
Display shows HC or HEAT COOL CONFLICT; the unit may not start.
|
Conflicting Heat/Cool Command | View Details |
| HI |
The display shows HI or HIGH TEMP, and the unit shuts down; water may feel very warm near the heater outlet.
|
High Water Temperature Lockout | View Details |
| HP |
Unit displays HP and shuts down; pool water is not heating, and the compressor stops shortly after startup.
|
High Refrigerant Pressure Trip | View Details |
| HPS |
Display shows HPS; the unit shuts down due to a safety lockout.
|
High Pressure Switch Open | View Details |
| LO |
The display shows LO or LOW TEMP, and the unit will not start or cycles off quickly.
|
Low Ambient Air Temperature Lockout | View Details |
| LOP |
Display shows LOP or LOW PUMP; the heater will not run.
|
Low Pump Speed / Flow Detected | View Details |
| LP |
The unit displays LP and will not heat; the compressor may attempt to start and then shut down.
|
Low Refrigerant Pressure Trip | View Details |
| LPS |
Display shows LPS; heater will not run.
|
Low Pressure Switch Open | View Details |
| OF |
The display shows OF or OFF, and the unit will not respond to thermostat changes.
|
External Control or Service Mode Active | View Details |
| PF |
The display shows PF or POWER FAIL; the unit may reset unexpectedly or lose settings.
|
Power Interruption / Low Voltage Fault | View Details |
| rF |
Display shows rF or REF; the unit will not heat and may lock out.
|
Refrigeration System Fault | View Details |
| SE |
Display shows SE or SENSOR; the heater locks out.
|
General Sensor Circuit Error | View Details |
| tS |
Display shows tS or TIMEOUT; unit attempts to start but times out.
|
Startup Timeout / No Heat Produced | View Details |
| – |
Display shows normal operation, but the fan does not run; the unit may shut down on high pressure.
|
Fan Not Operating | View Details |
| – |
Heater causes excessive vibration transmitted to pad or nearby structures.
|
Vibration / Mounting Issues | View Details |
| – |
Heater display is on but unit does not respond to button presses.
|
Unresponsive Keypad / User Interface Failure | View Details |
| – |
Heater is running but making loud grinding, squealing, or rattling noises.
|
Mechanical Noise from Fan or Compressor | View Details |
| – |
Heater runs but pool water does not reach set temperature; unit cycles on and off frequently.
|
Insufficient Heating Capacity or Short Cycling | View Details |
| – |
Heater trips the GFCI or breaker shortly after starting.
|
Electrical Ground Fault or Overcurrent | View Details |
| – |
Heater will not start at all; display is blank or dim.
|
No Power to AquaCal Heater | View Details |
| – |
Strong chemical or burning smell around the heater during operation.
|
Overheating Electrical or Chemical Off-gassing | View Details |
| – |
The fan runs, but the compressor does not start; no heating occurs.
|
Compressor Start Failure | View Details |
| – |
The heater cabinet shows corrosion, rust, or paint bubbling, especially near the coil and base.
|
Environmental Corrosion Damage | View Details |
| – |
The heater frequently goes into defrost and spends long periods not heating, even in mild weather.
|
Excessive Defrost Cycling | View Details |
| – |
The heater frequently shuts off when it rains or after heavy splashing from the pool.
|
Moisture Intrusion into Electrical or Sensor Components | View Details |
| – |
The heater operates, but causes a noticeable drop in water flow to pool returns.
|
Excessive Flow Restriction Through Heater | View Details |
| – |
Water leaking from the base of the AquaCal heater.
|
External Water Leak | View Details |
| – |
Water temperature overshoots the setpoint by several degrees before the heater shuts off.
|
Thermostat Overshoot / Control Hysteresis Issue | View Details |
No matching codes found
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